C.R.S. § 39-22-603.5

(1) As used in this part 6, unless the context otherwise requires, “frivolous return” means a return filed by any person that purports to be a return of the tax imposed by this article but that: (a) Does not contain information on which the substantial correctness of the return may be judged; or (b) Contains information that on its face indicates that the return is substantially incorrect; and (c) The conduct described in either paragraph (a) or (b) of this subsection (1) is due to either: (I) A position that is frivolous; or (II) A desire, which appears on the purported return, to delay or impede the administration of state income tax laws. (2) Intentionally left blank —Ed. (a) If any person files a frivolous return, the executive director may calculate the person’s Colorado taxable income and make an assessment based on such information as is available at the time the return is filed. (b) If the tax calculated by the executive director is greater than the amount theretofore assessed or paid, a notice of deficiency shall be mailed to the taxpayer by first-class mail as set forth in section 39-21-105.5 .